1. Field of the Invention
The present invention relates to an unloading mechanism for a palletized unit in a shelf storage system. In the present shelf storage system the goods to be stored are placed on unit pallets and supported on mobile storage and transport units in shelves. Each unit pallet on each transport unit moves on rails. Conveying mechanisms are provided for transport of the goods within the storage system to remove a unit load on a transport unit. Auxiliary mechanisms for loading and unloading of the shelves and also for driving, braking and holding position are used in the system and means are contemplated for counting and changing position of the storage and transport units.
2. Description of the Prior Art
The shelf storage system which is improved by the unloading mechanism of the present invention employs mobile four wheeled units for storage as disclosed in Buhler, U.S. Pat. No. 3,942,814, granted Mar. 7, 1976 and the shelf arrangement for unit load storage and conveyer movement is disclosed in Haldimann et al, U.S. Pat. No. 3,982,639, granted Sept. 28, 1976.
In order to remove storage units from a shelf, fork lift trucks have been used in the past as conveying vehicles which are manually driven through the lanes between the shelves. The lifting fork is applied to the desired shelf from which a unit is to be removed and a take-over apparatus mounted on the fork lift adapts the truck to remove the unit.
New improvements in the lateral displaceability of the take-over apparatus have made it possible to remove pallets from shelves without the fork lift truck having to be swung-in transversely to a shelf row. This improvement allows a very narrow design of the rows or shelves to a width of a few centimeters beyond that of the conveying vehicle. It is this narrow operating width to which the unloading mechanism of the present invention is adapted.
The individual shelf compartments within the shelf storage system are provided with rails which are inclined and it is on these rails that the storage units run. In the storage system there is provided, at the end of the shelf compartments, stop devices which prevent undesired movement at the ends of the rails thus assuring that there will be no failing of the storage units out of the shelf compartments. The conventional stops which have been used heretofore are formed in a hook-like shape but this causes a jumping up of the rolling transport unit with its loaded pallet brought about by the momentum and impact against the stop which frequently results in over jumping of the stop by the load on its pallet. It can easily be seen that the hook-like stops make removal of the rolling pallet from the shelf compartment much more difficult than if another stop could be used, especially since the hook-like stop must be swung out of the way of the storage unit. Thus, with the hook-like stop it is necessary to provide unlocking means which release the rolling pallets from the stops and raise the pallets above the stops.
It has already been proposed to use unlocking means for the rollers of the transport unit riding on the rails of the shelf in the location adjacent to the stops. This prior art unlocking means is arranged in a set of planes which are parallel to the planes of the rails so as to be freely rotatable on a common shaft and vertically adjustable. The two shaft ends of the common shaft are received in lateral slotted guides which make possible a parallel displacement of the shaft with simultaneous raising of the rollers. Using this solution for the problem of unlocking the roller unit one cannot manage without recourse to hydraulically actuatable plungers which must be mounted on the conveying vehicle and which have the essential track to provide for the parallel displacement of the shaft in the slotted guides with the conveying vehicle being in the coupled condition to the unlocking means.
An improved unlocking device of the parallel plane displacement type has been proposed which is simpler in design and comprises unlocking means which release the rolling storage units from the stops and which raise the same over the safety hooks to a take-out device. These unlocking means are provided with rollers which are mounted on that end of the take-out device near the shelf. The take-out device is generally of the lifting conveyer class and is turned towards the shelf opening. The rollers of the transport unit are mounted so as to be freely rotatable on a shaft which is perpendicular to the direction or displacement of the take-out apparatus. The ends of the perpendicularly oriented shaft project beyond the rollers and are used as guide bolts which cooperate with guideways situated in the region of the shelf opening. These guideways facilitate withdrawing of the unit load.
Although this improved system has given good results, it is expensive to build and has the disadvantage of a large number of moving parts which need constant maintenance and adjustment to prevent unwanted failure of operation.